Visualizing Schisto: Common parasite may increase women’s HIV risk

Washing day in Mozambique
Washing day in Mozambique
Flickr, domink raskin

In sub-Saharan Africa, the burden of schistosomiasis – a disease caused by water-borne parasitic worms – disproportionately affects females. What’s more, it may explain why women uniquely account for a greater percentage of people living with HIV/AIDS in Africa.

This differs starkly from other regions of the world where AIDS tends to affect men more than women.

Females, traditionally charged with cleaning the family’s laundry, often acquire schistosomiasis when washing clothes in rivers and other freshwater sources. The schistosomiasis worm migrates from its snail hosts in the water and burrows into the skin.

A report today in The Lancet by Sam Loewenberg examines large-scale efforts in Uganda to combat this common water-borne NTD (neglected tropical disease) with an expanded drug treatment program. Yet some of the experts and officials cited in the report say the battle will not be won without ensuring everyone has access to clean water and proper sanitation.

The screen grab below shows how rates of disability (suffering) from schistosomiasis in females in sub-Saharan Africa exceed those among males.

Schisto graph
UW, IHME

In a fascinating article in the New York Times, Donald McNeil, Jr. chronicles the work of Norwegian infectious disease experts led by Dr. Eyrun F. Kjetland in South Africa. The scientists are treating schistosomiasis in teenage girls in an attempt to heal the sores they develop in their vaginas when the worms burrow into the skin.

In their research, Dr. Kjetland and colleagues reported that women with these sores were three times more likely to have HIV. They think that the sores make women more susceptible to acquiring the virus.

Yet the idea that schistosomiasis raises females’ risk of acquiring HIV is still hotly debated.

In 2009, Dr. Peter J. Hotez, a leading tropical disease expert, president and director of the Sabin Product Development Partnership at the Sabin Vaccine Institute, and co-author of the Global Burden of Disease Study 2010, declared schistosomiasis treatment “Africa’s 32 cents solution for HIV/AIDS.” Other scientists are skeptical. Dr. Mark Dybul, executive director of the Global Fund to Fight AIDS, Tuberculosis and Malaria was interviewed in the New York Times article and noted that more evidence is needed before allocating AIDS funding to fight schistosomiasis.

Schistosomiasis
Wikipedia

While the verdict is still out on the link between schistosomiasis and HIV/AIDS, it’s clear that schistosomiasis is a threat to population health, especially among women. One to two months after infection, schistosomiasis can cause fever, chills, cough, and muscle aches. If it is not treated, the disease can cause abdominal pain, enlarged liver, and problems passing urine. It can also raise the risk of bladder cancer.

In sub-Saharan Africa in 2010, schistosomiasis was the ninth-leading cause of disability among females (see screen grab below). In males, it ranked 11th.

Schisto2The next screen grab shows the 25 leading causes of disability among females in different East African countries. As a cause of disability, schistosomiasis ranked as high as fourth and fifth in Mozambique and Malawi, respectively. Both of these countries also have a high burden of HIV/AIDS.

Schisto 3In South Africa, Dr. Kjetland and her colleagues are hard at work to answer a pressing public health question: Can schistosomiasis treatment lower girls’ chances of acquiring HIV?

Even though scientists have yet to establish a conclusive link between schistosomiasis treatment and prevention as a means to protect individuals from HIV, the threat of schistosomiasis is well-documented. And at as low a price as 8 cents per treatment, treatment is cheap.


Katie Leach-Kemon, a weekly contributor of global health visual information posts for Humanosphere, is a policy translation specialist from the University of Washington’s Institute for Health Metrics and Evaluation.

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About Author

Katie Leach-Kemon

Katherine (Katie) Leach-Kemon is a policy translation specialist at the Institute for Health Metrics and Evaluation (IHME). Katie specializes in two of IHME's research areas, the Global Burden of Disease and health financing. Katie has helped produce IHME's Financing Global Health report since it was first published in 2009. She received an MPH from the University of Washington and served as a Peace Corps volunteer in Niger. Her work has been published in The Lancet, Health Affairs, and the Journal of the American Medical Association. You can follow her on Twitter @kleachkemon.